LEP is the acronym of Large Electron Positron collider. This was the 27 km circumference electron/positron collider in service from 1989 to 2000 at CERN in Geneva.
The four ALEPH, OPAL, L3 and DELPHI detectors on the LEP were used to analyse the reaction products of those collisions where the bosons of the electroweak Weinberg / Salam / Glashow model could be found in quantity. The very precise measurements that were taken made it possible to validate the Standard Model, to prove the unlikelihood of the so-called technicolor models and to verify the prediction by cosmologists that there are only three families of light neutrinos in the universe.
The result of the LEP experiments showing the existence of only 3 families of light neutrinos in the universe.
The LEP was shut down and dismantled in 2001 to make room for its successor, the LHC, after having extended the values of the masses of possible supersymmetric particles, it is supposed to have given the first convincing signs of the existence of the Higgs boson.
-the history of the LEP.
View of the LEP while it was still in service (Credit: CERN).